Memristive devices, or memristors, are a new type of switchable devices with an electrically switchable device resistance. Memristive devices are both scientifically and technically interesting, and hold promise for non-volatile memory (NVM) and other fields. For NVM applications, the compatibility with matured CMOS technology requires the memristive devices to work in binary or other digital modes. The resistance value of a memristive device is used to define the binary or other multi-level digital states. Switching the memristive device reliably and repeatedly to desired states has been a major challenge. It is frequently observed that applying a voltage write pulse often produces large fluctuations in device resistance that exhibit a lognormal distribution. The wide range of such lognormal distribution of device parameters is a potential hinder for the usability, reliability and longevity of memristive devices.